1. Field of the Invention
The present invention relates to the positioning of plugs or screens by using horizontal drilling.
The present invention may be more particularly used in the field of working mineral deposits. Thus, in thick deposits or with a fairly steep slope where the gas, oil and water tend to separate by increasing density from top to bottom during working, under the effect of gravity, the methods of recovering oil by injection of gaseous miscible fluids, or possibly surface-active products in liquid solution, generally have a good volumetric efficiency allowing a good recovery of the oil. The products thus injected in small quantities into vertical or sloping wells are however distributed unevenly in the deposit because of the high flow speeds near the well and because of the frequent local natural barriers between the wells. The result is a waste of products and a loss of efficiency.
2. Description of the prior art
The prior art may be illustrated by the British patent Nos. GB-A-2 096 670 and GB-A-1 458 799 and by the U.S. Pat. No. 4,289,354.
According to the first document cited, fluids are injected into the deposit through vertical wells. This method requires the drilling of numerous wells and does not provide uniform distribution of the fluid. In addition, this prior method is more restricted in application than the method of the present invention which is in nowise limited to sloping reservoirs.